Antenna for radiotelegraphy



Se t; 11, 192&

ESPENSCHIED ANTENNA FOR RADIOTELEGRAPHY Filed Sept. 3, 1921 3 Sheets-Sheet 1 ATTORNEY Sept. 11, 1928.

' L. ESPENSCHIED ANTENNA FOR RADIOTELEGRAPHY Filed Sept. 1921 3 Sheets-Sheet 2 INVENTOR L. ly wmakieai N lIlL m. VII

W ATTORNEY Sept. 11, 1928.

L. ESPENSCHIED ANTENNA FOR RADIOTELEGRAPHY Filed Sept. 5. 1921 3 Sheets-Sheet INVENTOR LZfs Wenw/zwd ATTORNEY Patented Sept. 11 1928.

v a p L 1,683,716 UNI'TEDNSTATES PATENT. OFFICE.

LLOYD nsrnnsenimn, or Queens, New YORK. ASSIGNOR T'OIAMEYRICAN TELEPHONE AND .TELE RAPH OMPANY, A CORPORATION on NEW YORK.

. ANTENNA FOB RADIOTELEGRAPHY.-

" ap lication area September.

The principal fobject of-iny invention is to provide a new and improved system of antenna unitsfor radio receiving o'r tra-nsmitting. Another objectof my invention is to utilize an open-wire transmission line, or a portion thereof, for a radio antenna. -An other object of my invention is to sectionalize an open-wire transmission line without impairing its transmitting properties and to utilize the sections as units in a multiple antenna system. Still another object of my invention" is to provide a system of antenna units with individual high frequency apparatus, combining them in proper effective relation with a low frequency central station. These and other objects of my invention will become apparent upon'consideration of a few specific-examples which I have shown'inthe accompanying drawings, and which I will now proceedto describe. It will be understood that the invention is defined in the appended] claims, and in the following description I am referring to specific "examples of practice'thereunder. a

In the drawings, Figure 1 is a diagram of a system of antennae comprising sections of atransmission line ;-Fig. 2 is a diagram showing a modification; FigQS is a diagram showing a plurality of transmission lines sectionalized for antenna purposes and adapted to serve atthesame time as low frequency signaling conductors; F ig- 4: is adiagram showing a radio transm tting system comprising a sectionali'zed transmission line; Fig. 5 a diagram showingtheportion of a transmission line at an'elevated river cross ing utilized as a receiving antenna.

The two conductors 4 of the transmission line shown in F ig; lZhave respective interposed inductance coils 5 of comparatively low impedance 'for audio frequencies, but of high impedance to radio frequencies. Thus the transmission line is divided into the sections indicated by the numerals 1, 2 and 3.

' Across one end of each section is a bridge 6 with two condensers Tfin series and a branch 8 from a point between them going through the primary of transformer 9 to ground. The secondary of the transformer 9 connected in the usual way to the grid of the vacuum tube detector 10 whose output; or plate circuit 11 comprises the primary winding 12 "of the transformer whose secondariesi', are respectively in series with a, 1921. Serial No. asarss.

the conductors 4, each shunted by a condenser-145.. As much of the receiving-apparatus just described as is enclosed by the dotted rectangle is designated by the reference numeral 15. y 1

At one end of the transmission line is a telephone receiver 16. I A

' Eachtransmission line sectiomsuch as 1,

togethenwith theground connection 8 at its end, constitutes a radio receiving antenna. r 1 I 1 lhe nductances 5 prevent leakage oi the hen frequency currents"from 'this s Ct-ion into an adjoining section, sothat, With respect to radio frequencies, the several antennzefunction quite independently of one another. I

The lowor audio-frequency currents in the output circuit of thedetector 10 are appliedthrough the transformer 1-2-13, and since the inductances 5 are of low impedance for such frequencies, these currentsflow to the telephone receiver 16,1vl1eie their effect iscumulative from the multipleantenna sections. i e

T and 1a are of low impedance to the radio i:requency currents, and hence ifacilitatethe flew oi these currents through the primary It will be understood that the condensers of the transformer 9. On the other hand,

these condensers are of high impedance to the audio frequency currents w'hieh ac'cord ingly flow principally along the length of the transmission line conductors 4:. I 7

It would be a matter of considerable dllfi-.

culty and disadvantage to try to ca'rry the radio frequencies by wire tOfa considerable distance: For such ireq'ueii'cies, the dissipation of energy in wire conductionandthe" zitten'uation would be large". By my inventlon, the radio frequency currents are not carried from the respective antennae in which they are setup, but at eachsucli antenna they are detected, and their effect is converted into audio frequency .currents which: can readily be conveyed a "consider; able distance to a central station, there to energize a common indicator. It vvill'b'e seen that I have utilized the same conductors which form the antennaato serve as the conductors of the indicator circuit, and that "I am able to place the indicator station at any convenient point more or less remote from some, or all, of the antenna."

The antennae s" stemhere disclosed hasdirecti'onal selectivity. Each unit is directive,

, properly ceivingapparatus end.

consisting, as it does, of a long horizontal overhead portion grounded at one end.' By relating the section lengths to the wave lengths, the directional selectivity can be intensified. the length of each section one-quarter'ofa wave length. For receiving purposes, the use of the sec tionalized conductor,.as herediselosed, will assist in reducing interference from high frequencies which might be induced in the open=wire lines from neighboring electrical systems. If the exposure of the line is beyond. the portion that is. sectionahzed for antenna purposes, the end sectionicoils will substantially prevent the high frequency disturbance from enteringthe antennae. If the exposure is at av point close-to one of the sections-then the, disturbance will be principally confined to that antenna. In such a case, it might be desirable simply to omit the apparatus 15 for that antenna, in other-words, not to attempt to utilize the corresponding section of the line as an antenna. 1 a i The inductance windings 5, which serve to divide the line into sections for radio frequencies, maybe given the proper values, so-that they will function as loadingncoils for the audio frequency currents in the line. Fig. 2 illustrates a modification which may be introducediat the end of each section op posite to the receiving apparatus. At such a place the bridge 17 with two condensers is -put across the line, andthe ground connection 19 is made at a'point between the condensers. These condensersoli'er a high impedance to audio frequency currents, and hence they do not alter the, audio transmitting properties of the .line, but they ofler low impedance to radio frequency currents, and hence each. antenna unit becomes grounded at its distant end as well as through the receiving. apparatus at the re- .Thus each antenna becomes a so-called earth antenna, and for maximum efficiency it becomes desirable to make the antenna length equal to :rihalt wave length, or an integer multiple of a half wave length. If this condition is satisfied, the sectionalizing coils 5 can be omitted, whichmay be done by shunting them by throwing the switches '18 in Fig. 2. Thereupon the ground conductor 8 serves asthc ground connection forboth ends of the two antenna sections adjacent thereto. In this case thewhole arangement takes the iorm of an open-wireline well grounded through the receiving apparatus with respect to high fre' quency currents, but only very slightly with respectto audio frequencies, at points an integer multiple of a. half wave length apart; with suitable high-, frequency radio apparatus inthe groundleads.

Fig, 3 lllustratesa system comprising a A desirable ratiois to make filter. with its cut-ofi' at 2,500,

plurality of open-wircrtransmission circuits sectionalized for antenna purposes, one of these circuits being utilized as the indicator circuit for the antenna system, and the others serving for vire telephoneand telegraph communication independently of the radio, system.

In the caseof Fig. 3, I have shown a condenser 20 in shunt-to, each inductance winding 5, making the combination anti-resonant to the radio frequency. QThe, lowermost pair of conductors 4 serve asthe indicator circuitfor the; radio system. In, this case'the output circuit 11 fronrthereceiver 15 in.- cludes the primary winding 12 of the trans former. whose secondary winding 13, is bridged acrossathe line. At 23 and 23 I have shownthe well-known combination of elements which serve to separate the telephone and telegraph channels for composite of the line. Thus, although the line 4: is sectionalized and used as part of the antenna system, it is fully available for telephone communication between the telephones 21 and 21, and each of its conductors an be used as a telegraph line between the two telegra 11 stations 22.,at one end :uulthc two stationsf22 at thebtherendr here a plurality of overhead lines are workedasun, antenna system, as shown in Fig, :3, the sectionalizing apparatus 5, 20 should beintroduced at registering points on all the lines, foiyif any conductor of one sec tion' shouldlap past a conductor of the other section, the capacity eli'ectbetwecn them might afford a leakage for high frequency current.

In F ig,

l I have shown atransiuission line sectionalized and combined with radio transmitting apparatus. The sectionalizing of the line a is accomplished in the same way as alreadydescribed by means of. the coils 5 and the bridge 6-is provided through the condensers 7 with the grounded branch 8 the same as inthe earlier figures. A transmitter 25 and a generatorfl l of ,frequcucy, say, 5,000 cycles per second, are put across the line at any conveniently locatedcentral station. To the frequency 5,000, and the voice frequencies introduced at the transmitter '25, the coils 5 offer low impedance, so that these frequencies'fiow to the branch circuits 26, but not through the condensers 7. The branch circuit 26 branches again to two filters, Vin, F and F". F is a low-pass Thus it passes all the essential VOlCB fL'QQUQHClOSL but does not pass the 5,000 frequency. F is a band-pass filter withfits critical frequencies set to pass. the 5,000 frequcncy,.but to exclude the voice frequencies. The 5,000 frequency transu'iitted by the filter F goes to the distorting tube harmonic generator H, which gives an output radio frequency curthat goes to the modulator M through the phase adjuster 4 In the modulator M the radio frequency current from the generator H is modulated by the voice frequency current transmitted through the filter F and the modulated radio frequency current is impressed through the transformer 9 on units is secured by supplying the 5,000 frequency current from a common source, so that the high frequency generators H are kept accurately in step.

By the term terminal signaling apparatus, which is employed in certain of the following claims, I intend to cover generically either terminal transmitting apparatus or terminal receiving apparatus. In Figure 1, for example, terminal receiving apparatus has been shown as at Figure 16.

lVhat is claimed is:

1. A transmission line sectionalized as to high frequency currents by interposed inductances and respective detecting means to cooperate with each section to utilize it as a radio antenna.

2. A transmission line sectionalized as to high frequency currents by interposed inductances, respective means to cooperate with each section to utilize it as a radio antenna, and a central low frequency station in cooperative relation with all said sections.

3. A transmission line sectionalized as to high frequency currents by interposed inductances, respective means to co-operate with each section to utilize it as a radioantenna, and a central station having a low frequency circuit connection over the said transmission line to each said means at the respective sections.

4. A transmission line, elements interposed at intervals therein to give high impedance to radio frequency currents, but low impedance to audiofrequency currents, ground connections for the corresponding sections of the transmission line, elements in said ground connections offering low impedance to radio frequency currents and high impedanceto audio frequency currents, radio apparatus associated with said ground connections, radio apparatus connected to said transmission line, and an audio frequency connection from each of said apparatus with said transmission line.

5. A series of antennae conductively connected together for low frequency currents, reactance elements insulating'them from one another for high frequency currents, respective high frequency radio apparatus in combination with said antennae, and low frequency terminal signaling apparatus operatively associated with the entire series at one end thereof. i i

, 6. A series of antennae ,conductively con- ,nected together for low frequency currents, but in eflect insulated from one another for high frequency currents, respectivedetectors for said antennae, a common low frequency indicator, a plurality of parallel transmission lines all sectionalized alike to high frequency currents by interposed inductances, means combined with each section .to utilize all the conductors of the corre sponding section as'a radio antenna,'a low frequency central station connected by one of said transmission lines with allof said means, and low frequency sending and receiving apparatus connected with the other transmission lines. i

7 A plurality of antennae, like units of radio frequency apparatus associated respec tively therewith, a central station, and an audio frequency circuit connecting said station and said units of apparatus in serial order with said central station at one end of the series arrangement.

ated with each section and comprising a respective detector, an output low frequency circuit for each said detector connected to the line, and a cooperating low frequency indicator on the line. I

9. A transmission line with an elevated portion, inductances therein cutting off this portion from the remainder of the line with respect to radio frequencies but not low frequencies, and apparatus associated with said portion to utilize it as a radio antenna.

10. A transmission line sectionalized as to high frequency currents by interposed inductances, local means to co-operate with each section to utilize it as a respective radio antenna and terminal signaling means to cooperate with said local means.

11. A transmission line sectionalized as to high frequency currents by interposed inductances,'respective high frequency means to co-operate with each section as an individual radio antenna and extended low fre quency terminal signaling'means to co-operate with all the sets of high frequency means.

In testimony whereof I have signed my name to this specification this 30th day of August, 1921s j LLOYD ESPENSCHIED. 

